Defrosting device with heat extractor

ABSTRACT

A defrosting system for refrigeration equipment embodying a heat extracting reservoir for storing heat extracted from the hot gaseous refrigerant during normal operation of the refrigerating equipment so that this heat can be effectively utilized during a hot gas defrost cycle, thereby enabling an evaporator to be thoroughly defrosted in a relatively short period of time and an adequate supply of hot gas refrigerant to effectively defrost the evaporator without any condensation of the gaseous refrigerant occurring in the evaporator as it is defrosted.

United States Patent Redfern et al.

Oct. 1, 1974 DEFROSTING DEVICE WITH HEAT EXTRACTOR Primary Examiner-Meyer Perlin [76] Inventors: Howard W. Redfern, 121 Lookout fl xg ff gg O Bnen;

131.; William P. Coleman, 631 a y Martin St., both of Clarksville,

Tenn. 37040 [57] ABSTRACT [22] Filed: May 4, 1973 A defrosting system for refrigeration equipment embodying a heat extracting reservoir for storing heat ex- [21] Appl' 357092 tracted from the hot gaseous refrigerant during normal operation of the refrigerating equipment so that this [52] US. Cl. 62/196, 62/278 heat can be effectively utilized during a hot gas defrost [51] Int. Cl. F25b 47/00 cycle, thereby enabling an evaporator to be thor- [58] Field of Search 62/196, 277, 278, 81 oughly defrosted in a relatively short period of time and an adequate supply of hot gas refrigerant to effec- [56] References Cited tively defrost the evaporator without any condensation UNITED STATES P S of the gaseous refrigerant occurring in the evaporator 2,538,660 1/1951 Shreve 62/277 as defrosted" 2,698,522 1/1955 La Porte 2,770,104 11/1956 Sweynor 5 Chums 2 Drawmg Flgures 34 24 42 L v ,2 6 s Li'quid Rec-ever 26 I I l Com ressor I6 I I PATENIEU BUT 74 'q id Reciever DEFROSTING DEVICE WITH HEAT EXTRACTOR BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a dcfrosting device for use in domestic and small commercial, self-contained refrigeration equipment and includes a reservoir having a heat exchange liquid therein which extracts heat from the hot gas refrigerant as it flows from the compressorto the condenser during normal operation of the refrigeration equipment so that the heat stored in the heat exchange liquid may be extracted by the hot gas refrigerant during the defrost cycle to reduce the time necessary to effectively defrost the evaporator and to assure that the hot gas refrigerant will not condense in the evaporator during the defrost cycle.

2. Description of the Prior Art Conventional refrigeration equipment employs various arrangements for defrosting the evaporator periodically in order to maintain the evaporator free of accumulation of ice or frost. Such devices basically incorporate a bypass so that the hot gas refrigerant is discharged from the compressor through the evaporator rather than through the condenser and expansion device so that the hot gaseous refrigerant will melt any accumulation of frost from the evaporator coil. In some instances, auxiliary heating devices are employed to increase the temperature of or increase the volume of hot gaseous refrigerant available to the evaporator coil. Prior US. Pat. No. 3,256,708, issued to Howard W. Redfern discloses one type of auxiliary heater assembly for use in a defrosting system. Other patents which disclose defrost devices are U.S. Pat. No. 2,526,032, issued Oct. 17, 1950; US. Pat. No. 2,64l,908, issued June 16, 1953; and U.S. Pat. No. 1,980,688, issued Nov. 13, 1934. While auxiliary heaters are effective, the cost of installation, the initial cost of the equipment and the operating cost of the equipment may be relatively high. Also, devices which utilize a heat exchange liquid to store heat from the hot gaseous refrigerant during normal operation can only extract the heat which has been stored in the heat exchange liquid at a relatively slow rate in view of the restricted coil surface area.

SUMMARY OF THE INVENTION An object of the invention is to provide a defrosting device which includes a heat exchange coil in the hot gas refrigerant line between the compressor and condenser in which the coil is disposed within a container of heat exchange liquid for storing heat in the liquid from the hot gaseous refrigerant during the normal operation of the refrigeration equipment, so that the heat exchange liquid will be raised to a temperature substantially the same as the temperature of the hot gaseous refrigerant. A'second coil is immersed in the heat exchange liquid with the second coil being connected to the refrigerant line between the expansion device and evaporator on its discharge side and connected by a valve to the refrigerant flow line between the compressor and condenser on the downstream side of the coil which transfers heat to the heat exchange liquid during normal operation of the refrigerationequipment.

Another object of the invention is to provide a defrosting device in which the heat which has been stored in a heat storing device during normal operation of the refrigeration equipment over a relatively long period of time is more rapidly extracted from storage due to the increase in surface area contact of a heat exchange device during the defrost cycle thereby enabling the defrost cycle to be more quickly completed and to enable the defrosting operation to be more efficiently completed with no external heat being applied to the system.

A further object of the invention is to provide a de- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of the defrost device of the present invention illustrating the association of the heat reservoir and extractor with the other components of a typical refrigeration system.

FIG. 2 is a perspective view of the heat extractor with portions broken away illustrating the arrangement of the heat exchange coils in the liquid reservoir.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now specifically to FIG. 1, there is a schematic ilustration of a typical refrigeration system including a compressor 10, the discharge line 12 from the compressor to a condenser 14, a liquid refrigerant receiver l6 and a liquid refrigerant flow line 18 extending from the receiver to an evaporator 20 through an expansion device 22 which may be in the form of an expansion valve or capillary tube. The liquid refrigerant is expanded by absorption of heat in the evaporator and returns to the compressor through the suction line 24 and a low pressure side accumulator 26. The aforedescribed refrigeration system is completely conventional and is provided with the usual controls and the like normally found in domestic or small commercial refrigeration equipment in which the entire refrigeration unit is self-contained.

A defrost line 28 is communicated with the evaporator 20 and may be connected into the line in any desired manner on the downstream side of the expansion device 22. Normally, the defrost line 28 is connected to the discharge line 12 through a valve so that when the valve is opened, the hot gaseous refrigerant from the compressor will be discharged directly into the evaporator rather than passing through the condenser ,and receiver with the expansion device 22 serving as a one-way check valve to prevent reverse flow of the hot gaseous refrigerant and the normal resistance to flow through the liquid receiver and condenser which isat least partially filled with liquid preventingflow-ofrtheous refrigerant will proceed through the condenser dur ing the defrost operation.

In the present invention, there is provided a heat exchange device generally designated bynumeral 30 that is incorporated into the discharge line 12 and which includes a heat exchange coil 32 that forms a part of and is connected directly into the discharge line 12 by tubes or conduits 34. The coil 32 is disposed within a container or housing 36 that is suitably insulated with the housing 36 being substantially filled with a heat exchange liquid, such as water, or the like, with the coil 32 being immersed inthe heat exchange liquid so that during normal operation of the refrigeration system, heat will be extracted from the hot gaseous refrigerant by the heat exchange coil 32 due to the surface contact of the heat exchange liquid with the coil 32 thereby raising the temperature of the heat exchange liquid to substantially the same temperature as the hot gaseous refrigerant in the discharge line 12. Thus, during normal operation of the refrigeration system, such as when the refrigeration system is in a cooling mode, heat will be extracted from the hot gaseous refrigerant and stored in the heat exchange liquid within the container 36 whereby the container 36 and the liquid therein forms a heat reservoir and the coil 32, in effect, serves as a pre-condenser. From the coil 32, the hot gaseous refrigerant proceeds into the condenser 14 and is cooled and condensed therein in the usual manner. The construction of the coil 32 is such that it will not actually condense the hot gaseous refrigerant and will not alter the pressure on the high pressure side or discharge side of the compressor. Inasmuch as normal refrigeration cycles involve a cooling mode period of 6 to 8 hours, the construction of the coil may be such that the heat exchange liquid in the container will be raised substantially to the temperature of the hot gaseous refrigerant during the normal cycle of operation of the refrigeration system while in its cooling mode.

A second heat exchange coil 38 is immersed in the heat exchange liquid in the reservoir 36, and as illustrated in FIG. 2, the coil 38 may be concentrically arranged in relation to the coil 32 for optimum utilization of the space within the container and for optimum heat exchange relation with the liquid in the reservoir 36. The coil 38 is provided with a discharge line 40 connected with or forming an extension of the bypass line 28 and inlet line 42 connected with the discharge line 12 on the downstream side of the coil 32 and between the coil 32 and the condenser 14 as illustrated in FIG. 1. A valve 44, such as a solenoid operated valve, which is normally closed, is provided in the line 42 so that the valve 44 is open only when the refrigeration system goes into the defrost cycle. When this'occurs, the valve 44, being opened, will permit the hot gaseous refrigerant to flow through the coil 32 and then through the coil 38 and directly into the evaporator 20. Thus, the

v heat which has been stored in the heat exchange liquid in the reservoir 36 will be extracted and absorbed by the refrigerant passing through the coils 32 and 38 and be discharged into the evaporator thereby maintaining the temperature of the hot gaseous refrigerant-at substantially the normal temperature of the hot'gaseous refrigerant as it is discharged from the compressor thereby more rapidly defrosting the evaporator 20 inasmuch as the hot gaseous refrigerant passing into the evaporator will be at a higher temperature than normal and also providing a larger volume of hot gaseous refrigerant at a higher tmperature thereby more effectively defrosting the evaporator and assuring that the hot gaseous refrigerant will not be condensed in the evaporator during the defrost operation.

The utilization of the second coil 38 materially increases the surface area which is in contact with the heat exchange liquid in the reservoir 36 thereby increasing the heat transfer capacity of the heat extracting device 30 so that the heat stored in the heat exchange liquid in the reservoir over a relatively long period of time during the normal operating cycle of the refrigeration unit when it is in the cooling mode can be rather quickly extracted from storage and effectively safe storage life of items in a refrigerator which utilizes the heat extractor.

The heat extractor also effectively reduces the load on the compressor during start up and after defrost periods inasmuch as the hot gaseous refrigerant, being cooled, at least partially, in the reservoir 36 will reduce the pressure, at least temporarily on the high pressure side of the compressor thus reducing the load on the compressor motor during periods of start up and after the defrost period.

If the hot gaseous refrigerant is cooled sufficiently in the heat exchange device 30, the latent heat of evaporation of the refrigerant gas will be absorbed by the heat exchange liquid which, of course, will more rapidly heat the exchange liquid in the reservoir. Also, the container 36 may be provided with a filler plug 46 which may also be in the form of a fusible plug to serve as a safety measure and the container may be of any suitable size depending upon the requirements of the system and insulated in any suitable manner.

The foregoing is considered as illustrative only of the principles of the invention. Further. since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. In a refrigeration system having a compressor unit, a condenser, an expansion device and evaporator arranged in series relation and a hot gas bypass line communicating the discharge of the compressor directly with the evaporator during a defrost cycle and provided with a defrost valve that is open only when the refrigeration system is in a defrost mode, that improvement comprising a heat storing device adapted to extract heat from hot gaseous refrigerant passing from the compressor to the condenser during operation of the refrigeration system during a cooling mode, said defrost bypass line including a heat exchange coil associated with the heat storing device for extracting heat from the heat storing device when the refrigeration system is in a defrost mode thereby supplying auxiliary heat to the hot gaseous refrigerant passing through the defrost bypass line for more efficiently and rapidly defrosting the evaporator, said heat storing device including a reservoir having a heat exchange liquid therein. a heat exchange coil immersed in said liquid with the coil being connected into the refrigerant flow line from the compressor to the condenser whereby the heat exchange liquid will act as a pre-condenser and extract heat from the hot gaseous refrigerant passing from the compressor to the condenser, said bypass line including a heat exchange coil immersed in said heat exchange liquid in the reservoir, said heat exchange coil in the bypass line being on the downstream side of the bypass valve so that when the bypass valve is opened, the hot gaseous refrigerant from the compressor will flow through the heat exchange coil in the bypass line whereby the refrigerant will absorb heat from the heat exchange liquid in the reservoir.

2. The structure as defined in claim 1 wherein the heat exchange coil in the hot gaseous refrigerant line between the compressor and condenser and the heat exchange coil in the bypass line are concentrically arranged in relation to each other and in spaced relation to each other with both of said coils being immersed in the heat exchange liquid whereby hot gas refrigerant, during defrost mode, will first pass through the heat exchange coil in the hot gas refrigerant line, then through the bypass valve and the heat exchange coil in the bypass line for discharge directly into the evaporator on the downstream side of the expansion device.

3. The structure as defined in claim 2 wherein the combined surface contact area of both heat exchange coils with the heat exchange liquid enables extraction of stored heat from the heat exchange liquid at a substantially higher rate than absorption of heat from the hot gas refrigerant by the heat exchange liquid during operation of the refrigeration system during a cooling mode thereby enabling the defrost cycle to be rapidly completed.

4. A defrosting device for use on a refrigeration system having a hot gas bypass defrost line comprising a reservoir of heat exchange liquid, a heat exchange coil inserted in the hot gas refrigerant line on the high side of the compressor for extracting heat from the hot gas refrigerant when the refrigeration system is in a cooling mode with the heat exchange coil being in series relation with the compressor and condenser. a second heat exchange coil in the heat exchange liquid and being in series relation to the bypass line and first mentioned heat exchange coil with a defrost valve normally isolating the second heat exchange coil from the hot gas refrigerant line, said first heat exchange coil storing heat in the heat exchange liquid and both heat exchange coils extracting heat from the heat exchange liquid during the defrost cycle.

5. In a refrigeration system having a compressor unit. a condenser. an expansion device and evaporator arranged in series relation and a hot gas bypass line communicating the discharge of the compressor directly with the evaporator during a defrost cycleand provided with a defrost valve that is open only when the refrigeration system is in a defrost mode, that improvement comprising a reservoir of heat storing liquid, a heat exchange coil in the hot gaseous refrigerant line extending from the compressor to the condenser for extract.- ing heat from hot gaseous refrigerant passing from the compressor to the condenser during operation of the refrigeration system during a cooling mode, said hot gas bypass line including a heat exchange coil, both of said heat exchange coils being immersed in the heat storing liquid for extracting heat from the heat storing liquid when the refrigeration system is in a defrost mode at a rate faster than the heat was extracted from the hot gaseous refrigerant when the refrigeration system was operating in a cooling mode thereby supplying auxiliary heat to the hot gaseous refrigerant passing through the defrost bypass line for more efficiently and rapidly defrosting the evaporator.

=l =l l 

1. In a refrigeration system having a compressor unit, a condenser, an expansion device and evaporator arranged in series relation and a hot gas bypass line communicating the discharge of the compressor directly with the evaporator during a defrost cycle and provided with a defrost valve that is open only when the refrigeration system is in a defrost mode, that improvement comprising a heat storing device adapted to extract heat from hot gaseous refrigerant passing from the compressor to the condenser during operation of the refrigeration system during a cooling mode, said defrost bypass line including a heat exchange coil associated with the heat storing device for extracting heat from the heat storing device when the refrigeration system is in a defrost mode thereby supplying auxiliary heat to the hot gaseous refrigerant passing through the defrost bypass line for more efficiently and rapidly defrosting the evaporator, said heat storing device including a reservoir having a heat exchange liquid therein, a heat exchange coil immersed in said liquid with the coil being connected into the refrigerant flow line from the compressor to the condenser whereby the heat exchange liquid will act as a pre-condenser and extract heat from the hot gaseous refrigerant passing from the compressor to the condenser, said bypass line including a heat exchange coil immersed in said heat exchange liquid in the reservoir, said heat exchange coil in the bypass line being on the downstream side of the bypass valve so that when the bypass valve is opened, the hot gaseous refrigerant from the compressor will flow through the heat exchange coil in the bypass line whereby the refrigerant will absorb heat from the heat exchange liquid in the reservoir.
 2. The structure as defined in claim 1 wherein the heat exchange coil in the hot gaseous refrigerant line between the compressor and condenser and the heat exchange coil in the bypass line are concentrically arranged in relation to each other and in spaced relation to each other with both of said coils being imMersed in the heat exchange liquid whereby hot gas refrigerant, during defrost mode, will first pass through the heat exchange coil in the hot gas refrigerant line, then through the bypass valve and the heat exchange coil in the bypass line for discharge directly into the evaporator on the downstream side of the expansion device.
 3. The structure as defined in claim 2 wherein the combined surface contact area of both heat exchange coils with the heat exchange liquid enables extraction of stored heat from the heat exchange liquid at a substantially higher rate than absorption of heat from the hot gas refrigerant by the heat exchange liquid during operation of the refrigeration system during a cooling mode thereby enabling the defrost cycle to be rapidly completed.
 4. A defrosting device for use on a refrigeration system having a hot gas bypass defrost line comprising a reservoir of heat exchange liquid, a heat exchange coil inserted in the hot gas refrigerant line on the high side of the compressor for extracting heat from the hot gas refrigerant when the refrigeration system is in a cooling mode with the heat exchange coil being in series relation with the compressor and condenser, a second heat exchange coil in the heat exchange liquid and being in series relation to the bypass line and first mentioned heat exchange coil with a defrost valve normally isolating the second heat exchange coil from the hot gas refrigerant line, said first heat exchange coil storing heat in the heat exchange liquid and both heat exchange coils extracting heat from the heat exchange liquid during the defrost cycle.
 5. In a refrigeration system having a compressor unit, a condenser, an expansion device and evaporator arranged in series relation and a hot gas bypass line communicating the discharge of the compressor directly with the evaporator during a defrost cycle and provided with a defrost valve that is open only when the refrigeration system is in a defrost mode, that improvement comprising a reservoir of heat storing liquid, a heat exchange coil in the hot gaseous refrigerant line extending from the compressor to the condenser for extracting heat from hot gaseous refrigerant passing from the compressor to the condenser during operation of the refrigeration system during a cooling mode, said hot gas bypass line including a heat exchange coil, both of said heat exchange coils being immersed in the heat storing liquid for extracting heat from the heat storing liquid when the refrigeration system is in a defrost mode at a rate faster than the heat was extracted from the hot gaseous refrigerant when the refrigeration system was operating in a cooling mode thereby supplying auxiliary heat to the hot gaseous refrigerant passing through the defrost bypass line for more efficiently and rapidly defrosting the evaporator. 